ELCT564 Spring /9/20151ELCT564
6/9/20152ELCT564 Introduction to Microwave Engineering RF and microwave engineering covers frequency from 100 MHz to 1000GHz RF frequencies: MHz VHF RF frequencies: MHz UHF Microwave frequencies: GHz mmwave frequencies: GHz THz frequencies: >300 GHz
6/9/20153ELCT564 Why study them separately? Region of EM spectrum where neither standard circuit theory (Kirchoff) nor geometrical (ray) optics can be directly applied. Because of short wavelength, lumped element approximation cannot be used. Need to treat components as distributed elements: phase of V or I changes significantly over the physical length of a device For optical engineering λ << component dimensions
6/9/20154ELCT564 Approach Solve Maxwell’s equations and apply boundary conditions for the specific geometry. Hard to do for every device!!!! Analytical solutions exist only for some basic geometries and often must use numerical techniques In a lot of cases we can find V, I, P, Zo by using transmission line theory (use equivalent ckts) Not a lot of info on EM fields but sufficient for microwave and RF circuits As f increases need to use full-wave tools
6/9/20155ELCT564 Why study microwaves? More bandwidth or information can be realized at higher frequencies – essential for telecommunications Microwave/mm-wave travel by line-of-sight and are not bent by the ionosphere (such as AM signals) Most of them not affected by atmospheric attenuation (space com. or secure terrestrial com.) Higher resolution radars are possible at higher frequencies Various atomic & molecular resonances occur mwave/mm-wave/THz frequencies which are important for remote sensing, radio astronomy, spectroscopy, medical diagnostics, sensing of chemical.biological agents Can get a very good salary as an RF/mmwave engineer.
Patriot Defense System Surface Radar 6/9/20156ELCT564 Applications
Global Communication Systems for the Army Air Traffic Control 6/9/20157ELCT564 Applications
Global Positioning System Personal Communication Systems Wireless LANs 6/9/20158ELCT564 Applications
Monolithic Microwave/mm-wave Integrated Circuits MRI Remote Sensing Earth and Space Observations Applications 6/9/20159ELCT564
Cable and Satellite TV Aircraft and Automobile Anti-Collision Radar Applications 6/9/201510ELCT564
ApplicationFrequency AM broadcast KHz Shortwave radio3-30 MHz VHF TV (2-4)54-72 MHz VHF TV (5-6)76-88 MHz FM broadcast MHz VHF TV (7-13) MHz UHF TV (14-83) MHz Cell phones (US) , MHz GPS1227, 1575 MHz PCS (US) MHz Microwave Ovens2.45 GHz Bluetooth2.4 GHz a (wireless LAN)5.8 GHz Direct Broadcast Satellite Services GHz Collision avoidance radar77 GHz 6/9/201511ELCT564
Emerging High Frequency Applications Satellite High speed microprocessor Personal Communications Mobile Computing/WLAN Automotive Radar 6/9/201512ELCT564 DVD player 60-G Wireless HDMI Adaptive cruise control radar for automobiles 94 GHz Point-to-point/Multi-point links
Home Networks of the Future 6/9/201513ELCT564
Connected to Home Office Access to Corporate Networks Wireless Market Segmentation Access to Internet Service Providers Internet Service Providers Enables Video Applications Wireless Service Providers Access to PSTN GlobalDeployment 6/9/201514ELCT564
Wireless Engine 6/9/201515ELCT564
RF/Wireless Education: Multi-Disciplinary Device/Circuit Design Basic Electromagnetics System Integration Integration Concepts Advance CAD Techniques Current Technologies and Design Rules Modern Experimental Analysis for Circuits and Subsystems 6/9/201516ELCT564
Transmission Lines “Heart” of any RF/Wireless System Coaxial Cable Parallel-Plates Twisted-Pair Rectangular Waveguide 6/9/201517ELCT564
Transmission Lines Microstrip Coplanar Waveguide 6/9/201518ELCT564
Substrate Materials Semiconductors Organic Ceramics Glass Silicon11.8 GaAs13 FR Polyimide3.5 Alumina Quartz3.5 6/9/201519ELCT564
Advanced Printed Wiring Board Technology
Transmission Line Equivalent Circuit L zR z C z G z + - u(z,t) u(z+ z,t) + - zz i(z,t) i(z+ z,t)
Microwave Bands NameFrequency L GHz S GHz C GHz X GHz Ku GHz K GHz Ka GHz U40-60 GHz V50-75 GHz W GHz
EM Theory Review 6/9/201523ELCT564
Maxwell’s Equations 6/9/201524ELCT564
Fields in Media 6/9/201525ELCT564 Loss tangent
Fields at General Material Interface 6/9/201526ELCT564 Bn2 Bn1 Ht2 Ht1 Et2 Et1 Dn2 Dn Medium 1 Medium 2 Dn2 Dn1 h.....
Fields at General Material Interface 6/9/201527ELCT564 Et2 Et1 h Medium 2 Medium 1 Msn
Fields at a Dielectric Interface 6/9/201528ELCT564 Fields at the Interface with a Perfect Conductor Fields at the Interface with a Magnetic Wall
The Helmholtz Equation 6/9/201529ELCT564 Source-free, linear, isotropic, homogeneous Wave Equation/The Helmholtz Equation Propagation constant/phase constant/wave number
Plane Waves in a Lossless Medium 6/9/201530ELCT564 Assuming electric filed only have x component and uniform in x and y directions Phase velocity Wavelength What is the speed of light? Intrinsic Impedance
Plane Waves in a General Lossy Medium 6/9/201531ELCT564 Complex propagation constant: Attenuation constant and phase constant
Plane Waves in a General Lossy Medium 6/9/201532ELCT564
Plane Waves in a Good Conductor 6/9/201533ELCT ×10 -7 m 6.60×10 -7 m 7.86×10 -7 m 6.40×10 -7 m The amplitude of the fields in the conductor decays by an amount 1/e (36.8%) after traveling a distance of one skin depth
Summary of Results for Plane Wave Propagation in Various Media 6/9/201534ELCT564
General Plane Wave Solutions 6/9/201535ELCT564 i=x,y,z Separation of variables
Circularly Polarized Waves 6/9/201536ELCT564 Polarization of a plane wave refers to the orientation of the electric field vector: fixed direction or change with time. The plane waves which have their electric filed vector pointing in a fixed direction are called linearly polarized waves. Electric field polarization for (a) Right Hand Circularly Polarized (RHCP) and (b) Left Hand Circularly Polarized plane waves.
Energy and Power 6/9/201537ELCT564 A source of electromagnetic energy sets up fields that store electric and magnetic energy and carry power that may be transmitted or dissipated as loss. The time-average stored electric energy in a volume V The time-average stored magnetic energy in a volume V
Energy and Power 6/9/201538ELCT564 Power Ps delivered by the sources Poynting Vector (P 0 ): power flow out of the closed surface S. Power dissipated in the volume due to conductivity, dielectric and magnetic losses (P l )
Plane Wave Reflection from A Media Interface 6/9/201539ELCT564
Example 6/9/201540ELCT564 Consider a plane wave normally incident on a half-space of copper. If f=1GHz, compute the propagation constant, intrinsic impedance, and skin depth for the conductor. Also compute the reflection and transmission coefficients (Copper’s conductivity is 5.813×10 7 S/m).